I haven't driven it much because of the little problems that have surfaced since I put it together, but I am squashing them one at a time.

I had a problem where on corners and on acceleration I was losing power and jerking. I found the problem: Make sure your battery hasn't slipped! I had a problem where on corners and on acceleration I was losing power and jerking. I found the problem: Make sure your battery hasn't slipped! You can see how I was arc'ing to the battery hold down enough that it actually ate away part of the hold down!

Regarding boost, MBC will give you flat boost. On MS either used closed loop, or don't use it. If you really want EBC, you can buy one down the road. Having boost that doesn't do what you want is how to break a motor!

If you plot cylinder pressure vs crank position, tuning the way I just described will make keep peak cylinder pressures down (what breaks/bends stuff), while average cylinder pressures higher (makes power).

For absolute maximum power, tune fuel to about 12.8, then start adding timing till you get detonation or hit MBT. You'll detonate in boost most likely first. But you can't do that, if you do you'll bend rods at 230-250whp where you could make 300whp with better reliability keeping it high boost/rich/conservative timing.

I ran 17 PSI on a GT3271 with 550cc injectors at 100% duty cycle on a stock 99' motor reving to 7,800 and it never broke from power for a year of daily driving/beating on it. It died from the harmonic damper bolt vibrating out and destroying the keyway in the crank.

Regarding boost, MBC will give you flat boost. On MS either used closed loop, or don't use it. If you really want EBC, you can buy one down the road. Having boost that doesn't do what you want is how to break a motor!

I disagree. I can post lots of when I ran my mbc and it was a lot less flat than my current EBC in Open Loop. It would get to 10psi more lazily, and then start tapering toward redline. Currently with Open Loop it shoots straight to 11 and holds that all the way to redline. And yup, Open Loop, I've been lazy and haven't even tuned CL.

If you plot cylinder pressure vs crank position, tuning the way I just described will make keep peak cylinder pressures down (what breaks/bends stuff), while average cylinder pressures higher (makes power).

For absolute maximum power, tune fuel to about 12.8, then start adding timing till you get detonation or hit MBT. You'll detonate in boost most likely first. But you can't do that, if you do you'll bend rods at 230-250whp where you could make 300whp with better reliability keeping it high boost/rich/conservative timing.

Agree about the high boost + fat afr's + super low timing if you want to make the absolute most power on a stock LB. This, however, is ONLY true on a HUGE turbo. Try the same on a small one and you'll still break well before the 300whp mark.
Not even going to touch the 12.8:1 afr part cause that's just nuts and should not ever be done unless you're tuning a DI engine.

Quote:

I ran 17 PSI on a GT3271 with 550cc injectors at 100% duty cycle on a stock 99' motor reving to 7,800 and it never broke from power for a year of daily driving/beating on it. It died from the harmonic damper bolt vibrating out and destroying the keyway in the crank.

So the engine was completely and utterly perfect when you yanked it? Literally the only thing wrong with it was the crank keyway? Cause I vaguely remember you saying you broke that one too? Maybe I'm mistaken, I'd need to check my emails. If it was otherwise undamaged, that's pretty cool.

I'll look more into the "max powah!" aspect after I figure out the rest of this mess. The nose is coming off the car today and I am going to check all the charge piping and also try and work on my ducting. I was hitting 218 degrees cruising with both fans on last night, not even pushing it. When I turned on A/C it crept up to 2/3 of the gauge before I shut the A/C off. It was so nice having a nice cool cabin while it lasted though

Honestly, the power I was experiencing before pulling the turbo to be ported was perfectly fine. I realize I could have just let it creep/spike and I might be have been ok with a proper tune, but honestly I don't trust myself or my tuning abilities to tread that fine line.

I disagree. I can post lots of when I ran my mbc and it was a lot less flat than my current EBC in Open Loop. It would get to 10psi more lazily, and then start tapering toward redline. Currently with Open Loop it shoots straight to 11 and holds that all the way to redline. And yup, Open Loop, I've been lazy and haven't even tuned CL.

Agree about the high boost + fat afr's + super low timing if you want to make the absolute most power on a stock LB. This, however, is ONLY true on a HUGE turbo. Try the same on a small one and you'll still break well before the 300whp mark.
Not even going to touch the 12.8:1 afr part cause that's just nuts and should not ever be done unless you're tuning a DI engine.

So the engine was completely and utterly perfect when you yanked it? Literally the only thing wrong with it was the crank keyway? Cause I vaguely remember you saying you broke that one too? Maybe I'm mistaken, I'd need to check my emails. If it was otherwise undamaged, that's pretty cool.

Well for me, I always had a dual port external 38mm gate, and with that, a 20 dollar Ebay MBC was flat within a few kpa, and a low pressure paint gun regulator kept it withing about 1KPA plus or minus. I've seen people with open loop have boost change when the weather changes for comparison, not sure if you have this problem though. This was never a problem with any MBC I've run, they are solid and reliable in my experience.

Yeah I'm not saying for anyone here to run 12.8:1 in boost. Just saying that is, more or less, the best AFR for power IF YOU CAN RUN IT WITHOUT DETONATION. If you were burning race fuel, for example. Or water injection. I've done a lot of research and some testing (aka broke **** and went fast) and if you can supress the detonation the motor makes more power around 12.8 than it does at 10:1 or 11:1. It burns faster.

Vlad that old motor I bent the rods in it with nitrous, I've told this story here before. I bought the miata, put nitrous on it, had the controller mess up at the track and blew a HG/bent a few rods. I replaced the HG but it still vibrated/had slightly lower comp on a couple cylinders. Boosted it anyways. Motor looked fine when torn down, still had same compression as it did before, just a few bent rods which explained the vibration, the vibration is actually what caused the harmonic damper bolt to vibrate out and trash the keyway in the first place!

Short story is I've run 17 PSI on stock longblock, and 28 PSI on rods only longblock both with a GT3271. And while I've broken **** along the way, these motors are pretty damn tough all things considered.